1. Field of Invention
The present invention relates to power device controllers and more particularly to two loop power device controllers with current mode control.
2. Description of Related Art
Advanced electronic circuitry requires advanced power sources. The newer generations of power sources utilize power devices with corresponding control circuits, which are capable to drive the power devices with great precision and fast transient response. These control circuits are capable of reducing, or even eliminating traditional problems, such as the dependence of the output voltage on the operating temperature or load, the uneven dependence of the control mechanisms on the frequency, and so on.
Many power device controllers utilize one loop feedback. Typically this feedback loop operates in voltage mode control, sensing an output voltage, comparing it to a reference voltage, and using the generated error voltage to modify the operation of the power device, such as its duty cycle.
Other designs use two loop control circuits. In addition to the voltage mode control loop, these designs utilize a current mode control loop. This second loop senses the output current and uses this information to control the power device faster.
However, even in such advanced two-loop designs the control characteristics exhibit load dependences. Therefore, there is room for improvement in power device control circuits.